Fraunhofer ILT
Sample component produced in a resin bath from the HoPro3D system.
Researchers at the Fraunhofer Institute for Laser Technology (ILT) have developed a novel system, for producing high-resolution microcomponents by photo-crosslinking.
The project, given the name HoPro-3D, allows polymer microstructures to be produced economically and customised in one machine according to the institute.
The experts at Fraunhofer ILT worked with researchers from LightFab GmbH from Aachen, Bartels Mikrotechnik GmbH from Dortmund and Miltenyi Biotec GmbH from Bergisch Glabach. The 3D printer developed by the team combines fast two dimensional exposure, scrolling digital light processing (DLP) with a high-resolution laser process, multiphoton polymerisation (MPP) to produce microcomponents from photopolymers.
The HoPro-3D machine features two selectable exposure systems, for high build rates (scrolling DLP) or high precision (MPP). According to Fraunhofer ILT, the DLP module emits at a wavelength of 365 nm. This exposes the basic structures of a microcomponent with a pixel resolution of 10µm.
The femtosecond laser and the MPP module can be used to write contour lines with a resolution of around 2µm according to Fraunhofer ILT.
The institute says that the layer-by-layer approach makes it possible to build the finest MPP structures on top of already printed DLP structures, which quickly creates extended components with a complex structure and high-resolution details. The platform allows for the production of components with a footprint of up to 60 x 100 mm2.
The software of the HoPro-3D enables users to switch between the two exposure modules ‘smoothly’ according to the team. CAD data can also be used to decide when it makes sense to switch between the printing processes. During the layer-by-layer build-up of a component, it is possible to switch between the two processes several times.
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“The concept is in place and the corresponding machine has been built and already extensively tested,” said Dr. Martin Wehner, Head of the Biofabrication Group at Fraunhofer ILT. “After completion in spring 2022, the laboratory prototype could already be tested and optimised in an application-oriented manner as part of the Fraunhofer SiCellNet network.
“The SiCellNet cluster forms a central point of contact for research into new tools and manufacturing techniques for the analysis, sorting and provision of living cells. The performance of the combination plant and the control of the process could thus be optimally expanded.”
Funded by the SME Innovation Program, the Fraunhofer ILT team has been expanding the performance of DLP-based processes in a project titled “Precise assembly by high resolution seamless 3D printing – PANDA”. The knowledge gained in this project will be applied to the HoPro-3D system.
Fraunhofer ILT says that with the lack of need to switch between different machines, smaller functional elements can be integrated directly into larger 3D printed components. Also according to the company, a high local functional density of microscopic structures can be integrated into components during production.
The team says that the potential applications include microfluidic chips for laboratory diagnostics and rapid tests, micromechanical components and complete microfluidic systems for efficient point-of-care diagnostics close to the patient without need for further laboratory testing.
Fraunhofer ILT
Realization of MPP and DLP process in one resin bath.
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